1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device which prevents contact resistance due to a native oxide film from being increased.
2. Description of the Prior Art
As generally known in the art, in addition to the advancement of semiconductor techniques, development of high speed operation and high integration of semiconductor devices are in progress. Accordingly, fine adjustment and high integration of a pattern have been necessary. In accordance with such a tendency, various process techniques have been developed and used to obtain excellent device characteristics.
In particular, in order to improve the operation performance of semiconductor devices, new contact process techniques have been developed. In the contact process techniques, when a contact between upper and lower patterns is unstable or a contact resistance increases, although a fine adjustment of a pattern is achieved, the reliability of the semiconductor device is lacking and it is difficult to perform a high speed operation thereof.
Hereinafter, a conventional contact process will be briefly described.
FIGS. 1A through 1C are cross-sectional views which illustrate a conventional method of manufacturing a semiconductor device.
Referring to FIG. 1A, a silicon substrate 1 on which a predetermined lower structure having a junction region 2 is formed is prepared. An interlayer dielectric film 3 is deposited over a whole surface of the silicon substrate 1 to cover the lower structure. An etch mask, for example, a photoresist pattern 4 is formed on the interlayer dielectric film 3 by a known process. The photoresist pattern 4 defines a contact forming region.
Referring to FIG. 1B, the interlayer dielectric film 3 is etched by using the photoresist pattern 4. Consequently, a contact hole 5 exposing the junction region 2 is formed. The photoresist pattern 4 used as the etch mask is removed.
Referring to FIG. 1C, a conductive film, for example, a metal film is deposited on the interlayer dielectric film 3 so that the contact hole 5 is buried. The metal film is patterned to form a metal wiring 6 connected to the junction region 2 of the silicon substrate 1.
When forming the metal wiring 6, an intermediate plug material, namely, a polycrystalline silicon film 7 can be interposed between the metal wiring 6 and the junction region 2, as shown in FIG. 2. In FIG. 2, reference numeral 8 represents an oxide film.
Conventionally, when manufacturing the semiconductor device, etching residuals and a native oxide film of a substrate surface produced during a contact etching should be removed. In order to restore etching damage, after the contact hole is formed, plasma dry and wet cleaning processes are sequentially performed using NF3/O2, SF6/O2, CF4/O2, or Ar/O2 and then a metal film is deposited.
However, during the formation of a contact conductive film, since the deposition of a metal film in sputtering equipment or the deposition of a polycrystalline silicon film in chemical vapor deposition equipment is achieved after the washed substrate surface is exposed to air, as shown in FIG. 3, the formation of a native oxide film 10 at a contact surface is unavoidable. Accordingly, an exact ohmic contact between the metal wiring 6 and the junction region 2 of the silicon substrate 1 is not achieved, thereby increasing contact resistance. This causes the semiconductor device to be degraded.
Also, so as to solve the above problems, conventionally, prior to depositing the metal film, a physical sputtering is performed with Argon plasma as an in-situ preliminary treatment. In order to minimize the formation of a native oxide film by means of polycrystalline silicon film deposition equipment, a substrate is loaded into a substrate loading portion, in a state that the substrate loading part is separately closed and an oxygen concentration is reduced less than 100 ppm by flowing nitrogen of high purity, a door positioned between the substrate loading portion and a high temperature deposition tube, and the substrate is loaded into the high temperature deposition tube.
However, such steps minimize the influence of the native oxide film and do not provide a clean contact surface, causing the increase of the contact resistance according to badness of the contact surface.